The purpose is to isolate and characterize enzymes involved in the biosynthesis of lactose which are UDP glucose Pyrophosphorylase, UDP-galactose-4-Epimerase, and Lactose Synthetase. Lactose synthetase requires two proteins for activity, a galactosyltransferase and alpha-lactalbumin. This protein-protein interaction is studied by kinetics and chemical modification techniques. The galactosyltransferase is also involved in the biosynthesis of glycoproteins. BIBLIOGRAPHIC REFERENCES: Geren, C.R., Olomon, C.M. Primrose, D.C. and Ebner, K.E. (1977) Purification of UDP-Glucose Dehydrogenase by Hydrophobic and Affinity Chromatography. Preparative Biochemistry, 7, 19-31. Brown, R.C., Fish, W.W., Hudson, B.G., and Ebner, K.E. (1977) Isolation and Characterization of Rat alpha-Lactalbumin - A Glycoprotein. Biochem. Biophys. Acta, 491, 82-92.